1. Technical Field of the Invention
This invention relates generally to wireless communication systems and more particularly to radio frequency integrated circuits used in such wireless communication systems.
2. Description of Related Art
Wired and wireless communication systems are known to support communications between wireless and wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system typically is constructed, and hence typically operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards, including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof.
Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc., communicates directly or indirectly with other wireless communication devices. For direct communications (also known as point-to-point communications), the wireless communication devices utilize common channels (e.g., one of a plurality of radio frequency (RF) carriers of the wireless communication system) and communicate over those common channel(s). For indirect wireless communications, each wireless device communicates directly with an access point (AP) or associated base station (e.g., for cellular services) via an assigned channel. To complete a communication connection between the wireless devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, utilizing a public switch telephone network (PSTN), via a wide area network such as the Internet, and/or via another public or private packet data network.
For each wireless communication device to participate in wireless communications, it usually includes a built-in radio transceiver (i.e., receiver and transmitter) that is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). As is known, the transmitter includes a data modulation stage, one or more intermediate frequency (IF) stages, and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The one or more IF stages up convert the baseband signals with one or more local oscillations to produce RF signals. The power amplifier amplifies the RF signals prior to transmission via an antenna.
As is also known, the receiver is coupled to the antenna and includes a low noise amplifier, one or more IF stages, a filtering stage, and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The one or more IF stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or IF signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out-of-band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard.
The need for wireless networking has, heretofore, been addressed by various standards bodies that promulgate inter-working standards. The IEEE 802.11 standard that defines a wireless LAN. In a typical 802.11 wireless LAN, a wired backbone couples to one or more wireless access points (WAPs) that wirelessly connect to many computers or other electronic devices that contain wireless interfaces. IEEE 802.11 networks have achieved significant success in servicing wireless communication needs for portable computers, portable data terminals, and other wireless devices that transmit and receive data.
Wireless personal area networks (WPANs) enable short-range “ad-hoc” connectivity among portable consumer electronics and communication devices but do not require the infrastructure needed for an 802.11 network. The WPAN™ Study Group (SG) was formed on Mar. 12, 1998 by the IEEE 802.11 Working Group to investigate the need for a supplemental wireless network standard worked to create protocols for low power, low complexity, wireless connectivity among devices within or entering a device proximity. This includes devices that are carried, worn, or located near the body. These activities have led to the development of 802.15, which is a WPAN standard. These devices, however, typically support only paired communications between two devices.
Another known WPAN is Bluetooth. For both Bluetooth and 802.15 WPANs, the coverage area for a WPAN is generally within a 10-meter radius. In other words, a personal operating space (POS) is the space about a person that typically extends up to 10 meters in all directions and envelops the person whether stationary or in motion. It is within the POS that the portable device communicates with an access point. The Bluetooth radio system has emerged as the first technology addressing WPAN applications with its salient features of low power consumption, small package size, and low cost. Raw data rates for Bluetooth devices are limited to 1 Mbps, although the actual throughput is about half of the raw data rate.
A Bluetooth communication link supports up to three voice channels with very limited additional bandwidth for bursty data traffic. However, Bluetooth communication links cannot support the data transfer requirements of portable consumer electronics devices that transmit and receive multimedia data, e.g., high quality video applications, audio applications, and multi-megabyte file transfers for music and image files. In a typical Bluetooth communication channel, one of two paired devices establishes itself as a master to control communications with the other device, which, for that pairing, is the slave device.
Among other reasons, the above referenced systems are limited to paired communications between devices. For WLAN and cellular, all communications go through a network controller. For PAN systems that support peer-to-peer communications, those communications are also limited to a small number of devices (typically two). Even if the standard protocols supported peer-to-peer communications between multiple devices, interference and other problems make it difficult for such systems to proliferate in a reliable manner.
Therefore, a need exists for protocol and/or technology that support peer-to-peer communications between multiple devices in a manner that can reliably solve interference and related problems and that can support broadcast transmissions.